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United States Patent |
6,001,263
|
Working
,   et al.
|
December 14, 1999
|
Distiller's dried grain as oil dispersant
Abstract
A method and composition for dispersing oil. Distiller's dried grain is
applied to an oil spill or to an animal or object contacted with oil. The
distiller's dried grain sorbs and disperses the oil, allowing dispersal of
the oil in open water or removal of the oil from the animal or object.
Inventors:
|
Working; Gordon E. (Missoula, MT);
Moffatt; Lori C. (Missoula, MT);
Potter; Richard C. (Seeley Lake, MT)
|
Assignee:
|
Nurture Inc. (Missoula, MT)
|
Appl. No.:
|
209056 |
Filed:
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December 9, 1998 |
Current U.S. Class: |
210/691; 210/924 |
Intern'l Class: |
C02F 001/28 |
Field of Search: |
210/671,680,691,749,924,925
|
References Cited
U.S. Patent Documents
3394119 | Jul., 1968 | Luce et al. | 260/112.
|
3609096 | Sep., 1971 | Salomone | 252/352.
|
3676357 | Jul., 1972 | Ciuti et al. | 502/402.
|
3714063 | Jan., 1973 | Salomone | 252/312.
|
3793218 | Feb., 1974 | Canevari | 252/312.
|
3843517 | Oct., 1974 | McKinney et al. | 210/11.
|
3900421 | Aug., 1975 | Fusey | 252/312.
|
4098694 | Jul., 1978 | Perlaky | 525/312.
|
4110213 | Aug., 1978 | Tennant et al. | 252/312.
|
4224152 | Sep., 1980 | Lepain | 210/729.
|
4248733 | Feb., 1981 | States, Sr. | 252/355.
|
4382873 | May., 1983 | Gatellier et al. | 252/312.
|
4462910 | Jul., 1984 | Lepain et al. | 210/610.
|
4469603 | Sep., 1984 | Lepain et al. | 210/749.
|
4483716 | Nov., 1984 | Heller | 134/7.
|
4560482 | Dec., 1985 | Canevari | 210/749.
|
4597893 | Jul., 1986 | Byford et al. | 252/354.
|
4623468 | Nov., 1986 | Lepain et al. | 210/749.
|
4764285 | Aug., 1988 | Robbins et al. | 210/749.
|
4830759 | May., 1989 | Charlier | 210/749.
|
4978459 | Dec., 1990 | Bock et al. | 210/749.
|
5051192 | Sep., 1991 | Charlier | 210/749.
|
5082563 | Jan., 1992 | Webb et al. | 210/631.
|
5112495 | May., 1992 | Bartha et al. | 210/691.
|
5399350 | Mar., 1995 | Potter | 424/418.
|
Foreign Patent Documents |
740217 | Mar., 1970 | BE.
| |
197608 | Aug., 1976 | JP.
| |
Other References
H.I. Fuller, The Use of Floating Absorbents and Gelling Techniques for
Combating Oil Spills on Water, Journal Of The Institute Of Petroleum,
57(553) 35-43 (1971).
|
Primary Examiner: Cintins; Ivars
Attorney, Agent or Firm: Knobb, Martens, Olson & Bear, LLP
Parent Case Text
RELATED APPLICATIONS
This application is a continuation of U.S. patent application Ser. No.
09/046,211, filed Mar. 23, 1998, which is a continuation of U.S. patent
application Ser. No. 08/847,927, filed Apr. 28, 1997, which is a file
wrapper continuation of U.S. patent application Ser. No. 08/377,199, filed
Jan. 24, 1995, all now abandoned.
Claims
We claim:
1. A method for facilitating cleanup of environmental oil, comprising the
step of applying DDG to said environmental oil and permitting said oil to
become sorbed to said DDG.
2. The method of claim 1, wherein said oil is on a surface and said DDG is
applied to said surface.
3. The method of claim 1, wherein said oil is floating on an open body of
water.
4. The method of claim 3, wherein said oil is crude petroleum oil.
5. The method of claim 3, wherein said oil is a refined petroleum product.
6. The method of claim 3, wherein said DDG is in a floating, porous form.
7. The method of claim 3, further comprising the steps of permitting said
DDG to sorb said oil and then dispersing said DDG carrying said sorbed oil
in said water.
Description
FIELD OF THE INVENTION
The present invention is related to the use of natural grain material as an
oil dispersant. More specifically, the invention relates to the use of
distiller's dried grain as a dispersant of oil spills and as an agent for
cleaning surfaces contaminated with oil.
BACKGROUND
When an oil spill occurs, the most desirable remedy is recovery of the
spilled oil. However, rarely is more than 10% of the oil released in a
major spill ultimately recovered. Oil that cannot be recovered may be
dispersed, thus protecting shorelines, preventing the oiling of marine
birds and mammals, and speeding oil biodegradation. Oil dispersal has not
been universally satisfactory, however, mainly due to the high toxicity of
currently available dispersants.
Many dispersants are surfactant-based. However, there is reason to believe
that the efficacy of such dispersants is directly correlated with their
toxicity. A surfactant at a concentration sufficient to emulsify petroleum
may also be expected to have deleterious effects on marine organisms. Such
effects include tissue irritation, changes in gill membrane permeability
that promote asphyxiation and an increase in the uptake of chemical
pollutants.
Commercially available oil dispersants are all liquids and possess
relatively low LD.sub.50 s (high toxicity). These include COREXIT.RTM.
9527 (Exxon), a surfactant-solvent product for oil dispersal; NAXCHEM.RTM.
Dispersant K (formerly known as Conco Dispersant K and now sold by
Ruetgers-Nease), a product consisting primarily of surfactants and
alcohols; ATLANT'OL.RTM. AT-7 (Aspra, Inc.), a water-based product;
OMNI-CLEAN.RTM. OSD (Delta Omega Technologies), a water-based product
containing synthetic surfactants and fatty acid soaps and marketed as a
safe, low-toxicity product; COREXIT.RTM. 9550 (Exxon); and COREXIT.RTM.
7664 (Exxon), a product formerly marketed as an open-sea dispersant but
now sold mostly as a beach cleaner.
Surfactants added to oil slicks on water tend to be immediately diluted by
the water. Only when sufficient surfactant concentration is in contact
with both water and oil will dispersal occur. Once the surfactant has
solubilized the oil, the dispersed droplets mix with greater and greater
quantities of water. While this is the desired effect of dispersal, it
also tends to further dilute the surfactant concentration, so that
resurfacing of oil slicks may occur.
Related U.S. application Ser. No. 08/027,861, now U.S. Pat. No. 5,399,350,
discloses the use of a substantially intact proteinaceous particulate
material derived from grains as an oil emulsifier and high efficiency
dispersant. Exemplified materials typically have been milled, solvent
extracted, and separated from other components of grains. While this
material has excellent dispersal properties, it is somewhat expensive for
widespread use. Moreover, it is produced by an exacting process that
requires careful process control and dedicated production equipment. As a
result, the worldwide production capacity is currently insufficient to
permit large scale use on major oil spills.
Thus, there is a need for a lower cost, readily available, natural
non-toxic material useful as an oil dispersant that is available in large
quantities. The present invention provides such a material and a method
for using it in remediation of environmental spills.
SUMMARY OF THE INVENTION
The raw material for most commercial ethanol production is cereal crops,
such as wheat and corn. The spent, dried grains recovered after alcohol
fermentation, termed distiller's dried grain (DDG; also known as dried
distiller's grain or distiller's spent grain) or distiller's dried grain
with soluble material recycled back (DDGS) are largely a waste material
with few commercial uses. We have now discovered that DDG and DDGS
materials are effective as oil spill dispersants. This particulate
material, which is essentially insoluble, in contrast to liquid
dispersants, is not subject to the emulsion-breaking effects of dilution
after dispersal occurs. Similarly, because of this particulate nature, the
dispersant of the present invention can be used without suffering
deleterious dilution effects during or after dispersal. It has the major
advantages of the grain-based oil spill dispersants previously disclosed,
and is available at much lower cost and in much higher quantities.
One embodiment of the present invention is an oil dispersant composition,
comprising DDG. According to one aspect of this embodiment, the DDG is
formed into a solid mass having air or other gas entrained therein in
sufficient quantities that the composition will float on water.
Advantageously, the grain is fermentable. Preferably, the grain is oats,
wheat, corn, barley, rice or rye; most preferably, the grain is corn. In
addition, the composition may include solubles added back to the DDG. The
DDG composition is advantageously ground in an attrition mill prior to
application. Preferably, the DDG including solubles is a (-)50 U.S. mesh
fraction. According to another aspect of this embodiment, the DDG
composition is formed through foaming the DDG with a blowing agent during
pelletization or extrusion. Advantageously, the DDG is extruded or
pelletized with a binder. Preferably, the binder is a long chain fatty
acid, fatty acid ester or metal salt thereof. Examples of such binders
include, but are not limited to, stearic acid, calcium stearate and zinc
stearate. The DDG composition may be coated with a material that is
insoluble in water but soluble in oil. The DDG may also be mixed with an
active culture of a bacterium that biodegrades oil. The oil is preferably
crude petroleum oil or a refined petroleum product.
The present invention also includes a method for facilitating cleanup of
environmental oil, comprising the step of applying DDG to the
environmental oil and permitting the oil to become sorbed to the DDG.
Advantageously, the oil is on a surface and the DDG is applied to the
surface. Preferably, the surface is an animal body. In another aspect of
this embodiment, the oil is floating on an open body of water. The oil may
be either crude petroleum oil or a refined petroleum product. The DDG is
preferably in a floating, porous form. Further, the DDG may be allowed to
sorb the oil and then the DDG carrying the sorbed oil may be dispersed in
the water.
Another embodiment of the present invention is a method for remediating
hydrocarbons in contaminated soil, comprising admixing DDG or DDGS and the
soil, whereby the DDG or DDGS binds to the hydrocarbons. The hydrocarbons
may be aliphatic, aromatic or a mixture thereof. Preferably, the DDG or
DDGS is admixed with the soil by plowing. The method may further comprise
the addition of petroleum-degrading bacteria to the soil. Preferably, the
hydrocarbons and the DDG are present in a ratio of between about 100:1 and
about 0.1:1; most preferably, the ratio is between about 10:1 and about
1:1.
DETAILED DESCRIPTION OF THE INVENTION
DDG and DDGS are commercially available from a number of sources, including
Alcotech, Ringling, Mont. These are essentially waste material by-products
remaining after the fermentation of grain during alcohol production. This
material is natural, non-toxic, biodegradable, readily available and
extremely inexpensive. In fact, the dried DDG was sold by Alcotech as
animal feed at an approximate price in 1994 of $ 0.07 USD per pound. DDG
may be obtained after the fermentation of a number of grains, including
corn, wheat, barley, oats, rice and rye, although the use of DDG derived
from any grain as an oil dispersant is within the scope of the present
invention. DDG or DDGS may be used intact as large macroscopic
particulates, or may advantageously be ground in an attrition mill such as
a hammer mill or pin mill or may be processed, chopped, or otherwise
comminuted in a conventional manner to produce material having smaller
particle sizes. Median particle size may be determined by milling
parameters, by using a series of graduated sieves or by particle size
analysis. Furthermore, in applications requiring more exacting control
over the particle sizes, more advanced particle sizing apparatus and
methods are available to those of skill in the art.
As used herein, U.S. mesh size refers to the number of openings between
sieve wires per linear inch. The "(-)" designation before the mesh size
(i.e. (-)50 mesh) refers to the material which has passed through the
mesh. U.S. mesh sizes are conventional in the art and correspond to
specific particle sizes produced upon passing a material through the mesh.
The particulate materials of the present invention are capable of being
used in conjunction with the cleanup and/or control of spills or release
of unwanted or dangerous agents into the environment, including the
cleanup and control of crude oil spills or refined petroleum product
spills in open water; cleanup of other lipophilic or oily materials on
open water; and cleanup of similar materials from solid surfaces, such as
rocks, beaches, floors, soils, and living creatures such as birds and
mammals.
The particulate materials may be introduced to an area of oil released upon
a body of water. Thereafter, the DDG sorbs the oil, dispersing it so that
it is more easily assimilated into the environment. This method of
providing a colloidal dispersion of oil is particularly efficacious, since
microbial degradation of the oil can more easily occur. Oil degrading
bacteria may also be combined with the DDG compositions of the present
invention to promote removal of the oil during and after dispersion. Such
bacteria are well known in the art and are commercially available.
DDG can absorb a wide variety of substances, including hydrophobic
materials such as oils. When placed on an oil slick, the DDG first absorbs
oil, forming an in situ emulsifiable concentrate. Subsequent wave, wind,
and current action without further human interaction will create an
emulsion that acts to disperse the oil into the water column. Thus, DDG
offers an alternative solution to the problem of dispersing spilled oil.
Moreover, it does so without adding large amounts of toxic materials to
the oceans. In fact, DDG is derived from an edible cereal grain product
and as such is harmless to marine animals.
It will be appreciated that the DDG may either be administered as a powder
to the surface of the water containing the oil, or may be formed into
readily-dispersible solid forms, such as foams, tablets, agglomerates,
granules or pellets (a convenient mode of storage and application).
Principally, however, whatever mode of administration is chosen, it is
preferred that the DDG be prepared in a buoyant form so that it will float
freely upon the upper layer of oil. This will facilitate maximum contact
between the DDG and the oil. To achieve these objectives, a variety of
well-known production techniques can be used including lyophilization,
forming of pellets containing a blowing agent (e.g., carbon dioxide),
followed by dissipation of the blowing agent with resulting formation of a
foamed, low-density solid; and binding the DDG with a variety of binders,
fillers, or excipients. Preferred binders include long-chain fatty acids,
fatty acid esters or metal salts thereof such as, for example, magnesium
stearate. Typically, it is preferred that binders be used in
concentrations ranging from about 0.1 to 0.5 parts binder to one part DDG.
In order to permit the DDG to preferentially absorb oil instead of water,
it may be coated with an oil-soluble, water-insoluble coating, such as a
wax. Techniques such as molding and extrusion can be used to form foamed
or non-foamed DDG into macroscopic shapes.
The amount of DDG applied to the oil spill will vary with the amount of oil
to be removed. Generally, the DDG can remove from about 30% to about 90%
of the oil with which it comes in contact. One may attempt to disperse
most of the oil or only a small portion of it. Typically, 1-5 grams of oil
can be dispersed by 1 gram of DDG. This can serve as a guideline to those
of skill in the art in selecting the desired amount of DDG to apply to any
particular spill.
In addition to dispersion of oil on open water, the dispersants of the
present invention may be used to clean marine birds and mammals soiled by
petroleum products. The DDG will sorb the oil, allowing its removal by
rinsing with water. The DDG may also be applied to beaches and rocks to
sorb and remove spilled lipophilic contaminants such as petroleum or
petroleum products.
In addition, the DDG or DDGS may be used to remediate contaminating
hydrocarbons from soil. These materials, when admixed with contaminated
soil, will bind to and immobilize the hydrocarbon compounds, resulting in
their accelerated degradation by promoting the growth of oil-degrading
bacteria which occur naturally in the soil. This accelerated degradation
is due, in part, to the high nutrient content of the DDG. An inoculum of
petroleum-degrading bacteria may also be added to the soil to further
promote hydrocarbon breakdown. Because the hydrocarbons bind to DDG which
is insoluble, the migration of the hydrocarbons is essentially precluded
while microbial degradation is occurring.
The hydrocarbons may be either aliphatic, aromatic or a mixture thereof. In
a preferred embodiment, between about 0.01 parts and about 1 part of DDG
is admixed with 100 parts of soil contaminated with hydrocarbons. In a
preferred embodiment, the ratio of hydrocarbons to DDG (w/w) is between
about 100:1 and about 0.1:1. In a particularly preferred embodiment, the
ratio is between about 10:1 and about 1:1.
Although the preferred method of admixing the DDG and the contaminated soil
is by plowing, any method capable of resulting in admixture of the DDG and
the soil is within the scope of the invention. These materials offer
distinct advantages over fertilizers which are water-soluble and would
thus enter the water table. The dispersants of the present invention are
not water soluble and would thus not lead to ground water contamination by
the hydrocarbons bound thereto.
Further details, objects and advantages of the present invention will be
apparent through a review of the following examples.
EXAMPLE 1
PREPARATION OF SYNTHETIC SEAWATER
Synthetic seawater for use in experiments of the present invention was
prepared in the following manner:
______________________________________
Ingredient Concentration (g/L)
______________________________________
NaCl 17.10
MgCl.sub.2 .cndot. 6 H.sub.2 O
7.73
Na.sub.2 SO.sub.4
2.85
CaCl.sub.2 .cndot. 2 H.sub.2 O
1.06
KCl 0.48
NaHCO.sub.3 0.14
______________________________________
Following dissolution of all ingredients, the solution is adjusted to pH
8.0.+-.0.1 with concentrated hydrochloric acid or sodium hydroxide. As
will be appreciated, this formulation is identical to the Environmental
Protection Agency's (the "EPA") regimen. See 40 CFR, Part 300, Subpart J.
EXAMPLE 2
PROTOCOL FOR TESTING OIL DISPERSION PROPERTIES OF DDG
In order to test the oil dispersion and emulsification properties of DDG
and DDGS, we devised a protocol that combines features of the EPA's
standard method and the Labofina (rotating flask) method.
In general, a two-liter beaker containing 1 L of synthetic seawater
(prepared in accordance with Example 1) is placed in a Model G76 orbital
shaker (New Brunswick Scientific, Edison, N.J.).
Standard curves for test oils are obtained as follows: Approximately 0.07 g
of oil is added to a 10.0 ml volumetric flask, which is then filled to the
mark with chloroform. Dilutions are made with the following concentrations
of oil: 3500, 1750, 875, 350, 175, and 87.5 mg/L. Absorbance at 620 nm is
measured for all solutions, as well as for a chloroform blank, and a
standard curve for the oil is calculated by the method of least squares.
Oil (1.0 g) is added dropwise to the water. The dispersing agent is then
sprinkled onto the oil slick. The shaker is started immediately and run at
approximately 140 rpm, or about 50% of full scale. This speed was chosen
because it appears to yield the most realistic wave action in the beaker
without causing spillage. The shaker is stopped after 60 minutes and a
grab sample (ca. 50 ml) is taken from 4-5 cm below the water surface using
a large dropper. Exactly 25.0 ml of this sample is pipetted into a
separatory funnel containing 25.0 ml of chloroform, and the pipet is
rinsed by drawing the chloroform into it and ejecting it back into the
funnel. The funnel is then stoppered and shaken for 60 seconds. The water
and chloroform layers are allowed to separate, and the chloroform layer is
drawn off and filtered through anhydrous sodium sulfate. A sample of the
chloroform layer is taken and its absorbance is read at 620 nm. The
concentration of the oil in the chloroform (and therefore in the water
sample) is calculated from a standard curve. Percent efficiency is defined
as:
##EQU1##
We have found that one gram is the optimum amount of test oil to use. If
larger amounts of oil are used, so that the water:oil ratio falls below
about 1000, the percent efficiency begins to fall off; the dispersal
process appears to be water-limited under those conditions. If the
quantity of oil is less than 1 g, the amount of oil lost by adhesion to
the inner surface of the beaker above the water line becomes significant.
The oil dispersant properties of corn DDG and DDGS were determined as
described below.
EXAMPLE 3
Oil dispersant properties of corn DDG and DDGS
Approximately 272 g of corn DDGS and 130 g corn DDG were obtained from
Alcotech, Ringling, Mont. 0.200 g DDG was applied to 1.01 g North Slope
(NS) crude oil obtained from Shell Oil, Anacortes, Wash., in one liter of
seawater and shaken according to the protocol of Example 2 for 1 hour at
room temperature. The DDG was pin milled to a median particle size of
about 125 .mu.m (120 U.S. mesh) and 0.200 g of the pin milled material was
applied to 1.00 g NS crude oil in one liter of seawater and shaken for 1,
2, 19.5, 24, 48 and 72 hours.
DDGS (100.2 g) was ground in a food processor and passed through a 50 U.S.
mesh sieve (297 .mu.m), since it did not grind well in a pin mill due to
its high oil content. The yield was 4.6 g of the (-)50 U.S. mesh material.
0.200 g was applied to 1.00 g NS crude oil in 1 liter of seawater and
shaken for 19 hours.
The absorbance values at 620 nm were measured at these time points and are
indicated in Table 1. These materials performed well in dispersant tests
and did not agglomerate.
TABLE 1
______________________________________
Sample OD.sub.620
% efficiency
______________________________________
DDG-1 h 0.059 39.4
DDG-Pin Mill-1 h 0.093 63.5
DDG-Pin Mill-2 h 0.080 54.4
DDG-Pin Mill-19.5 h
0.072 48.9
DDG-Pin Mill-24 h 0.094 64.2
DDG-Pin Mill-48 h 0.123 84.4
DDG-Pin Mill-72 h 0.128 87.9
(-) 50 mesh DDGS 0.061 41.2
______________________________________
EXAMPLE 4
Oil Dispersant Properties of Wheat DDG
Wheat DDG (Alcotech) was pin milled twice in a Kitchen Mill (K-Tec, Orem,
Utah) to a (-)120 U.S. mesh particle size (125 .mu.m) and 0.200 g was
applied to 1.04 g NS crude oil in 1 liter of sea water and shaken for 1
hour 20 minutes. The absorbance at 620 nm was 0.065 which translated to an
efficiency of 37.1%.
EXAMPLE 5
Oil Dispersant Properties of Oat DDG
Oat DDG (Alcotech) was either extracted with hexane to remove the oil or
was left intact. Both samples were processed in a Kitchen Mill to (-)120
U.S. mesh (125 .mu.m). The standard protocol was followed using one liter
of sea water adjusted to pH 8.02, 1.0 g NS crude oil and 0.2 g DDG. The
hexane-extracted DDG gave an absorbance of 0.068 at 620 nm after 60 min,
corresponding to an efficiency of 35.8%. The non-extracted DDG gave an
absorbance at 620 nm of 0.088 at 60 min, corresponding to an efficiency of
46.8%.
EXAMPLE 6
Cleaning of Wildlife
Another application of the DDG and DDGS dispersants of the present
invention is in the cleaning of oiled wildlife. As will be appreciated,
with every oil spill, much of the oil is deposited on the beaches and on
the animals and vegetation that surround the affected area. The
particulate dispersants of the present invention will cleanse these
objects.
To demonstrate this phenomenon, pheasant wings are dipped twice into 1600
ml of synthetic seawater in a 2 liter beaker through an oil layer
containing 10 g of NS crude oil. Generally, the DDG or DDGS is spread on a
wing, then gently wiped off to agglomerate and remove loose oil, then a
second application is made and worked into the wing with tap water to sorb
the remaining oil. Finally, the wing is rinsed off with lukewarm water.
The wings are air-dried, and their weights before and after oiling, as well
as their weights after cleaning and drying, are compared. The DDG and
DDGS-treated wings will result in the removal of a significant amount of
oil.
EXAMPLE 7
Cleaning of Oiled Beaches
Beaches and shoreline rocks may be cleaned in a similar manner to the
cleaning of animals. For example, through spreading the dispersants of the
present invention on a beach, and scrubbing them into the sand and over
the rocks, the dispersants will naturally sorb the oil. Thereafter, the
beach front may be rinsed, or in the alternative, the natural wave action
will carry the dispersant-associated oil out to sea. Advantageously, if
the oil spill is pretreated with the dispersants of the present invention
prior to being deposited on the shoreline, it will exhibit significantly
less adhesion to beaches, rocks and other surfaces.
EXAMPLE 8
Remediation of Hydrocarbons in Soil by DDG
About 0.1 g of DDG is admixed with about 100 grams of moist soil containing
about 1 g aliphatic hydrocarbons. A control experiment is also performed,
using an identical soil sample to which no DDG has been added. The two
soil samples are monitored for hydrocarbon breakdown over time by
extraction with methylene chloride followed by gas chromatography
analysis. The soil sample to which DDG has been added will show a more
enhanced attenuation and/or elimination of hydrocarbon peaks on the GC
chromatogram compared to the control soil sample, indicating the induction
of bacterially-promoted hydrocarbon breakdown by the DDG.
While particular embodiments of the invention have been described in
detail, it will be apparent to those skilled in the art that these
embodiments are exemplary, rather than limiting, and the true scope of the
invention is that defined in the following claims.
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